Method of producing semiconductor optical device

Abstract

The invention discloses a method of producing on a substrate a semiconductor optical device having a laser diode and an EA optical modulator. An etched side face of a first semiconductor portion is formed. Then, for example, a first optical confinement layer and an active layer both for the EA optical modulator are grown by the metal organic vapor phase epitaxy method. The first optical confinement layer is grown by supplying hydrogen chloride in addition to a material gas. When the first optical confinement layer is grown, the formation of a thick semiconductor layer along the etched side face, which is an abnormally grown semiconductor layer, is decreased. Subsequently, the active layer for the EA optical modulator is grown. This method can suppress the active layer for the EA optical modulator from bending caused by the abnormally grown semiconductor layer.

1. A method of producing an integrated semiconductor optical device, the method comprising the steps of:
 (a) preparing a substrate having a main surface having: 
 (a1) a first area for forming a first semiconductor optical device to be included in the integrated semiconductor optical device; and 
 (a2) a second area for forming a second semiconductor optical device to be included in the integrated semiconductor optical device; 
 (b) forming on the substrate a semiconductor laminate for forming the first semiconductor optical device; 
 (c) forming an insulating-film mask on the semiconductor laminate on the first area; 
 (d) etching the semiconductor laminate by using the insulating-film mask to form on the first area a first semiconductor portion having a side face extending in a specified direction perpendicular to the main surface; 
 (e) after the etching of the semiconductor laminate, selectively growing a first semiconductor layer for the second semiconductor optical device through a metal organic vapor phase epitaxy method while leaving the insulating-film mask unchanged; and 
 (f) while leaving the insulating-film mask unchanged, selectively growing on the first semiconductor layer a second semiconductor layer for the second semiconductor optical device; 
 wherein in growing the first semiconductor layer, an etching gas containing a halogen element is supplied in addition to a material gas for the growing of the first semiconductor layer. 
 
     
     
       2. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein in the step of growing the first semiconductor layer, the mixing ratio of the material gas and the etching gas containing a halogen element is controlled to grow a semiconductor layer having a flat surface. 
     
     
       3. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein in the step of growing the first semiconductor layer, the first semiconductor layer is grown at a temperature of 600° C. to 640° C. 
     
     
       4. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein the first semiconductor layer for the second semiconductor optical device comprises a buffer layer. 
     
     
       5. A method of producing an integrated semiconductor optical device according to  claim 4 , wherein the buffer layer for the second semiconductor optical device is made of InP. 
     
     
       6. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein the first semiconductor layer for the second semiconductor optical device comprises an optical confinement layer. 
     
     
       7. A method of producing an integrated semiconductor optical device according to  claim 6 , wherein the optical confinement layer for the second semiconductor optical device is made of InGaAsP. 
     
     
       8. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein the second semiconductor layer for the second semiconductor optical device is an active layer. 
     
     
       9. A method of producing an integrated semiconductor optical device according to  claim 8 , wherein the active layer for the second semiconductor optical device has a multiquantum well structure made of InGaAsP. 
     
     
       10. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein in the step of growing the second semiconductor layer, the second semiconductor layer is grown by a metal organic vapor phase epitaxy method and an etching gas containing a halogen element is supplied in addition to a material gas for the growing of the second semiconductor layer. 
     
     
       11. A method of producing an integrated semiconductor optical device according to  claim 1 , the method further comprising a step of growing on the second semiconductor layer a third semiconductor layer for the second semiconductor optical device by a metal organic vapor phase epitaxy method;
 wherein in growing the third semiconductor layer, an etching gas containing a halogen element is supplied in addition to a material gas for the growing of the third semiconductor layer. 
 
     
     
       12. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein the semiconductor laminate comprises an active layer for the first semiconductor optical device. 
     
     
       13. A method of producing an integrated semiconductor optical device according to  claim 12 , wherein the active layer for the first semiconductor optical device has a multiquantum well structure made of InGaAsP. 
     
     
       14. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein:
 (a) one of the first and second semiconductor optical devices comprises a laser diode and the other one comprises an electroabsorption optical modulator; and 
 (b) the first and second semiconductor optical devices are optically coupled together with a butt-joint structure. 
 
     
     
       15. A method of producing an integrated semiconductor optical device according to  claim 1 , wherein as the etching gas containing a halogen element, hydrogen chloride is used. 
     
     
       16. A method of producing an integrated semiconductor optical device according to  claim 15 , wherein hydrogen chloride having a concentration of 5% is supplied at a flow rate of equal to or less than 20 sccm.